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Ctesibius
Ctesibius or Ktesibios or Tesibius ( grc-gre, Κτησίβιος; fl. 285–222 BC) was a Greek inventor and mathematician in Alexandria, Ptolemaic Egypt. He wrote the first treatises on the science of compressed air and its uses in pumps (and even in a kind of cannon). This, in combination with his work ''On pneumatics'' on the elasticity of air, earned him the title of "father of pneumatics." None of his written work has survived, including his ''Memorabilia,'' a compilation of his research that was cited by Athenaeus. Ctesibius' most commonly known invention today is a pipe organ (hydraulis), a predecessor of the modern church organ. Inventions Ctesibius was probably the first head of the Museum of Alexandria. Very little is known of his life, but his inventions were well known. It is said (possibly by Diogenes Laërtius) that his first career was as a barber. During his time as a barber, he invented a counterweight-adjustable mirror. Another invention of his included the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Clock
A water clock or clepsydra (; ; ) is a timepiece by which time is measured by the regulated flow of liquid into (inflow type) or out from (outflow type) a vessel, and where the amount is then measured. Water clocks are one of the oldest time-measuring instruments. The bowl-shaped outflow is the simplest form of a water clock and is known to have existed in Babylon, Egypt, and Persia around the 16th century BC. Other regions of the world, including India and China, also have early evidence of water clocks, but the earliest dates are less certain. Some authors, however, claim that water clocks appeared in China as early as 4000 BC. Water clocks were also used in ancient Greece and ancient Rome, described by technical writers such as Ctesibius and Vitruvius. Designs A water clock uses the flow of water to measure time. If viscosity is neglected, the physical principle required to study such clocks is Torricelli's law. There are two types of water clocks: inflow and outflo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Organ
The water organ or hydraulic organ ( el, ὕδραυλις) (early types are sometimes called hydraulos, hydraulus or hydraula) is a type of pipe organ blown by air, where the power source pushing the air is derived by water from a natural source (e.g. by a waterfall) or by a manual pump. Consequently, the water organ lacks a bellows, blower, or compressor. The hydraulic organ is often confused with the hydraulis. The hydraulis is the name of a Greek instrument created by Ctesibius of Alexandria. The hydraulis has a reservoir of air which is inserted into a cistern of water. The air is pushed into the reservoir with hand pumps, and exits the reservoir as pressurized air to blow through the pipes. The reservoir is open on the bottom, allowing water to maintain the pressure on the air as the air supply fluctuates from either the pumps pushing more air in, or the pipes letting air out. On the water organ, since the 15th century, the water is also used as a source of power to driv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydraulis
The water organ or hydraulic organ ( el, ὕδραυλις) (early types are sometimes called hydraulos, hydraulus or hydraula) is a type of pipe organ blown by air, where the power source pushing the air is derived by water from a natural source (e.g. by a waterfall) or by a manual pump. Consequently, the water organ lacks a bellows, blower, or compressor. The hydraulic organ is often confused with the hydraulis. The hydraulis is the name of a Greek instrument created by Ctesibius of Alexandria. The hydraulis has a reservoir of air which is inserted into a cistern of water. The air is pushed into the reservoir with hand pumps, and exits the reservoir as pressurized air to blow through the pipes. The reservoir is open on the bottom, allowing water to maintain the pressure on the air as the air supply fluctuates from either the pumps pushing more air in, or the pipes letting air out. On the water organ, since the 15th century, the water is also used as a source of power to dr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vitruvius
Vitruvius (; c. 80–70 BC – after c. 15 BC) was a Roman architect and engineer during the 1st century BC, known for his multi-volume work entitled ''De architectura''. He originated the idea that all buildings should have three attributes: , , and ("strength", "utility", and "beauty"). These principles were later widely adopted in Roman architecture. His discussion of perfect proportion in architecture and the human body led to the famous Renaissance drawing of the ''Vitruvian Man'' by Leonardo da Vinci. Little is known about Vitruvius' life, but by his own descriptionDe Arch. Book 1, preface. section 2. he served as an artilleryman, the third class of arms in the Roman military offices. He probably served as a senior officer of artillery in charge of ''doctores ballistarum'' (artillery experts) and ''libratores'' who actually operated the machines. As an army engineer he specialized in the construction of ''ballista'' and '' scorpio'' artillery war machines for sieges. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pipe Organ
The pipe organ is a musical instrument that produces sound by driving pressurized air (called ''wind'') through the organ pipes selected from a keyboard. Because each pipe produces a single pitch, the pipes are provided in sets called ''ranks'', each of which has a common timbre and volume throughout the keyboard compass. Most organs have many ranks of pipes of differing timbre, pitch, and volume that the player can employ singly or in combination through the use of controls called stops. A pipe organ has one or more keyboards (called '' manuals'') played by the hands, and a pedal clavier played by the feet; each keyboard controls its own division, or group of stops. The keyboard(s), pedalboard, and stops are housed in the organ's ''console''. The organ's continuous supply of wind allows it to sustain notes for as long as the corresponding keys are pressed, unlike the piano and harpsichord whose sound begins to dissipate immediately after a key is depressed. The smallest po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greeks In Egypt
The Egyptiotes, also known as Egyptian Greeks ( el, Αιγυπτιώτες), have existed from the Hellenistic period until the aftermath of the Egyptian revolution of 1952, when most were forced to leave. Antiquity Greeks have been present in Egypt since at least the 7th century BC. Herodotus visited ancient Egypt in the 5th century BC and claimed that the Greeks were one of the first groups of foreigners that ever lived there. Diodorus Siculus claimed that Rhodian Actis, one of the Heliadae, built the city of Heliopolis before the cataclysm; likewise the Athenians built Sais. Siculus reports that all the Greek cities were destroyed during the cataclysm, but the Egyptian cities including Heliopolis and Sais survived. First historical colonies According to Herodotus (ii. 154), King Psammetichus I (664–610 BC) established a garrison of foreign mercenaries at Daphnae, mostly Carians and Ionian Greeks. In 7th century BC, after the Greek Dark Ages from 1100–750 BC, the ci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alexandria
Alexandria ( or ; ar, ٱلْإِسْكَنْدَرِيَّةُ ; grc-gre, Αλεξάνδρεια, Alexándria) is the second largest city in Egypt, and the largest city on the Mediterranean coast. Founded in by Alexander the Great, Alexandria grew rapidly and became a major centre of Hellenic civilisation, eventually replacing Memphis, in present-day Greater Cairo, as Egypt's capital. During the Hellenistic period, it was home to the Lighthouse of Alexandria, which ranked among the Seven Wonders of the Ancient World, as well as the storied Library of Alexandria. Today, the library is reincarnated in the disc-shaped, ultramodern Bibliotheca Alexandrina. Its 15th-century seafront Qaitbay Citadel is now a museum. Called the "Bride of the Mediterranean" by locals, Alexandria is a popular tourist destination and an important industrial centre due to its natural gas and oil pipelines from Suez. The city extends about along the northern coast of Egypt, and is the largest city on t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mirror
A mirror or looking glass is an object that Reflection (physics), reflects an image. Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the direction of the image in an equal yet opposite angle from which the light shines upon it. This allows the viewer to see themselves or objects behind them, or even objects that are at an angle from them but out of their field of view, such as around a corner. Natural mirrors have existed since prehistoric times, such as the surface of water, but people have been manufacturing mirrors out of a variety of materials for thousands of years, like stone, metals, and glass. In modern mirrors, metals like silver or aluminium are often used due to their high reflectivity, applied as a thin coating on glass because of its naturally smooth and very Hardness (materials science), hard surface. A mirror is a Wave (physics), wave reflector. Light consis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arcesilaus
Arcesilaus (; grc-gre, Ἀρκεσίλαος; 316/5–241/0 BC) was a Greek Hellenistic philosopher. He was the founder of Academic Skepticism and what is variously called the Second or Middle or New Academy – the phase of the Platonic Academy in which it embraced philosophical skepticism. Arcesilaus succeeded Crates of Athens as the sixth scholarch of the Academy around 264 BC. He did not preserve his thoughts in writing, so his opinions can only be gleaned second-hand from what is preserved by later writers. In Athens Arcesilaus interacted with the Pyrrhonist philosopher, Timon of Phlius, whose philosophy appears to have influenced Arcesilaus to become the first Academic to adopt a position of philosophical skepticism, that is, he doubted the ability of the senses to discover truth about the world, although he may have continued to believe in the existence of truth itself. This brought in the skeptical phase of the Academy. His chief opponent was his contemporary, Zeno of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siphon
A siphon (from grc, σίφων, síphōn, "pipe, tube", also spelled nonetymologically syphon) is any of a wide variety of devices that involve the flow of liquids through tubes. In a narrower sense, the word refers particularly to a tube in an inverted "U" shape, which causes a liquid to flow upward, above the surface of a reservoir, with no pump, but powered by the fall of the liquid as it flows down the tube under the pull of gravity, then discharging at a level lower than the surface of the reservoir from which it came. There are two leading theories about how siphons cause liquid to flow uphill, against gravity, without being pumped, and powered only by gravity. The traditional theory for centuries was that gravity pulling the liquid down on the exit side of the siphon resulted in reduced pressure at the top of the siphon. Then atmospheric pressure was able to push the liquid from the upper reservoir, up into the reduced pressure at the top of the siphon, like in a baromet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silchester
Silchester is a village and civil parish about north of Basingstoke in Hampshire. It is adjacent to the county boundary with Berkshire and about south-west of Reading. Silchester is most notable for the archaeological site and Roman town of Calleva Atrebatum, an Iron Age and later Atrebates Celtic settlement first occupied by the Romans in about AD 45, and which includes what is considered the best-preserved Roman wall in Great Britain and the remains of what may be one of the oldest Christian churches. Location The present village is centred on Silchester Common. It is about west of the Church of England parish church and former manor house (now Manor Farm), which are in the eastern part of the former Roman town. Local government Silchester is a civil parish with an elected parish council. Silchester parish is in the ward of Pamber and Silchester, part of Basingstoke and Deane District Council and of Hampshire County Council and all three councils are responsible for dif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
